The mechanisms involved in the regulation of production and release of alveolar macrophage lysosomal enzymes are important to inhalation toxicology because of their participation in the digestion of endocytosed foreign materials and their role in the induction of lung damage during their release. The induction of lysosomal enzymes by morpholine in alveolar macrophages was examined. Morpholine produced a non-uniform response in the stimulation of lysosomal enzyme synthesis and its effect dependent on the sex of the animal from which the alveolar macrophages were obtained.